(a) Field of the Invention
The present invention relates to a sewage treatment apparatus which is used in a satellite treatment plant. The sewage treatment apparatus introduces a part of sewage from a sewer trunk line; performs sewage treatment; and supplies reuse water to the neighborhood. The present invention also relates to a sewage reuse system which includes a plurality of sewage treatment apparatuses located in respective satellite treatment plants.
(b) Description of the Related Arts
Conventionally, sewage flowing through a sewer trunk line is treated by a terminal sewage treatment plant in order to generate reuse water. The generated reuse water is supplied to an area on the upstream side. However, the supply of reuse water has become a problem for an area that is far away from the terminal sewage treatment plant but needs water.
Then, in recent years, satellite treatment plant, by which sewage can be effectively treated and reused, is put into use. FIG. 4 is an explaining diagram showing a structure of a plurality of satellite treatment plants. As shown in FIG. 4, there is a sewer trunk line 3. A terminal sewage treatment plant 2 is arranged at the end of the sewer trunk line 3, and a plurality of satellite treatment plants 1 are distributed along the sewer trunk line 3. Each satellite treatment plant 1 introduces a part of sewage flowing through the sewer trunk line 3; purifies the sewage in order to generate reuse water; then supplies the generated reuse water to an area that is in the neighborhood of the satellite treatment plant 1 and is in demand for reuse water.
However, because such conventional satellite treatment plan is often located in an urban district where it is difficult to secure ample setting space, it has become a problem to miniaturize the setting space as much as possible.
As disclosed in the Japanese Patent Publication No. 2008-705, the present applicant once proposed a sewage treatment apparatus used in such satellite treatment plant. The Japanese Patent Publication No. 2008-705 describes a sewage treatment apparatus which performs a sewage treatment through combining a high-rate filtering section with a membrane separation active-sludge treating section.
According to the sewage treatment apparatus disclosed in the Japanese Patent Publication No. 2008-705, it is possible to miniaturize the setting space of the whole treatment apparatus, as well as to generate reuse water with high purity.
However, it is necessary to generate reuse water according to the demand of the neighborhood. Furthermore, it is also necessary to prepare water tanks for temporarily storing the generated reuse water according to different purities. Because of that, there is an important project to generate reuse water and control water storing quantity of reuse water according to the demand for reuse water, but this project has not been considered in the Japanese Patent Publication No. 2008-705 mentioned above.
Therefore, in order to accomplish the project mentioned above, the present invention aims to control the water storing quantity of reuse water which is generated by a sewage treatment apparatus of a satellite treatment plant. Furthermore, the present invention also aims to control and adjust water storing quantities in a plurality of sewage treatment apparatuses by a unified management.